java-BaseDao

package dao;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;


public class BaseDao {
	private static String driver;
	private static String url;
	private static String user;
	private static String pwd;
	protected Connection conn;
	private static void init(){
		Properties properties=new Properties();
		InputStream is=BaseDao.class.getClassLoader().getResourceAsStream("basedao.properties");
		try {
			properties.load(is);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		driver=properties.getProperty("driver");
		url=properties.getProperty("url");
		user=properties.getProperty("user");
		pwd=properties.getProperty("pwd");
		
		try {
			Class.forName(driver);
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	static{
		init();
	}
	
	protected Connection getConnection(){
		try {
			if (conn==null||conn.isClosed()) {
				conn=DriverManager.getConnection(url,user,pwd);
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return conn;
	}

	protected void closeAll(Connection conn,PreparedStatement ps,ResultSet rs) {
		if (rs!=null) {
			try {
				rs.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			
		}
		if (ps!=null) {
			try {
				ps.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
		if (conn!=null) {
			try {
				conn.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
	
	protected int executeUpdate(String sql,Object... param) {
		int result=0;
		conn=getConnection();
		PreparedStatement ps=null;
		try {
			ps=conn.prepareStatement(sql);
			for (int i = 0; i < param.length; i++) {
				ps.setObject(i+1, param[i]);
			}
			result=ps.executeUpdate();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally{
			closeAll(conn, ps, null);
		}
		return result;
	}
	
	protected ResultSet executeQuery(String sql,Object... param) {
		ResultSet rs=null;
		conn=getConnection();
		PreparedStatement ps=null;
		try {
			ps=conn.prepareStatement(sql);
			for (int i = 0; i < param.length; i++) {
				ps.setObject(i+1, param[i]);
			}
			rs=ps.executeQuery();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return rs;
	}
	
}